<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      function say() {
        let a = function () {
          console.log("a");
        };
        a();
      }
      say();
      // a();
    </script>
  </body>
</html>
